Planing bottom for boats



July 1, 1952 I P. R. CREWE 2,501,836

I PLANING BOTTOM FOR BOATS Filed Jan. 24, 1951 1 s Sheets-Sheet 1 July1, 1952 P. R. CREWE 2,601,335

PLANING BOTTOM FOR BOATS Filed Jan. 24, 1951 3 Sheets-Sheet 2 July 1,1952 P. R. CREWE PLANING BOTTOM FOR BOATS.

Filed Jan. 24, 1951 Patented July 1, 1952 PLANIN G BOTTOM FOR BOATSPeter Rowland Crewe, Shanklin, Isle of Wight, England, assignor toSaunders-Roe Limited, Osborne, East Cowes, lsle of Wight, EnglandApplication January 24, 1951, Serial No. 207,546

In Great Britain January 26, 1950 4 Claims. 1

This invention has for its principal object to provide a flying boat orother marine aircraft having a hull of streamline form in place of thenormal planing bottom hull.

The invention provides a hull for a marine aircraft, which is generallyof streamline form and having fitted to its undersurface, at a locationnear to the centre of gravity, a flap which is movable, about atransverse axis, between a retracted position in which it lies flushwith the undersurface of the hull and a projected position, in which itsforward end is accommodated in a recess in the hull and its rearward endprojects beneaththe hull to constitute a step. In flight, the flap willbe retracted and the hull, being of streamline form, will have an airdrag comparable with that of the fuselage of a convenient land plane.

The flap may be movable from retracted to projected position, and viceversa, by any convenient mechanism, e. g. by means of a hydraulic orelectrical power unit. The pivotal axis of the flap is preferably soplaced that the resultant water load on the flap during movement thereofacts thereon at a location close to the pivotal axis.

The flap, when projected, constitutes a step which fulfils a similarfunction to the main step on the planing bottom of an orthodox flyingboat. The front wall of the cavity in the hull into which the front endof the flap lifts, when the flap is moved to projected position, forms ashelf which reflects and, to some extent at least, transforms intouseful energy the spray thrown forward from the step, thus reducing thewater drag on the hull during take-off. Ducts are provided in the cavityinto which the front end of the plate rises for ejecting laterally thespray thrown back from dropped afterbody fulfils the same function as.

the afterbody of an orthodox flying boat, i. e. it

keeps the trim and drag within reasonable limits at hump speeds andmid-planing speeds, it keeps the tail free from water, and gives goodlongitudinal stability at all speeds above the hump speed.

(i. e. the speed at which the trim and drag are at a maximum). Thedropped afterbody also avoids trouble due to suction of water such aswould be encountered on the undersurface of the rear part of a hullshaped like a conventional fuselage, i. e. tapering upwardly from theflap to the stern.

Two alternative embodiments of the invention will now be described indetail, by way of example, with reference to the accompanyingdiagrammatic drawings, in which:

Fig. 1 is a side elevation of a flying boat according to the inventionin flight,

Fig. 2 is a similar view showing the boat about to alight on the water,

Figs. 3 and 4 are respectively sections on the lines IIIIII and IVIV inFig. l,

Fig. 5 is a side elevation of the fiapon a larger scale,

Fig. 6 is a section on the line VI-VI in Fig. 5,

Fig; 7 is a side elevation of the bow plate,

Fig. 8 is a corresponding plan view, and

Fig. 9 isa side elevation of an alternative embodiment of flying boat.

The drawings, being diagrammatic, show the hull only of the flying boat,the wings and tail planes being omitted.

Considering first of all Figs. 1-8, it will be seen that the hull ill ofthe flying boat is of generally streamline shape, and has no step. Theafterbody of the hull is however dropped, its undersurface I l extendingparallel to the centre line of the hull.

Within a recess 12 (Fig. 5) in the hull is fitted a flap l3 which isrotatable about a transverse pivot 14 from the retracted position, shownin full lines, and the projected position shown in chaindotted lines.The pivotal axis ll of the flap I3 is at its upper surface andapproximately midway in the length of the flap, and the resultant waterload on the flap during movement thereof acts at a location close to thepivotal axis.

As will be seen, when the flap i3 is retracted,

its undersurface is flush with the undersurface,

of the hull Hi. When projected, however, the flap l 3 constitutes a stepwhich fulfils a similar function to the main step of an orthodox flyingboat hull. The flap is located with its centre below or somewhat forwardof the centre of gravity of the aircraft. The front wall l5 (Fig. 5) ofthe cavity l2 in the hull constitutes, when the flap is in projectedposition, a shelf which reflects rearwardly part of the spray thrownforward from the step. Ducts 18 are provided in the walls of the hulland these ducts serve to eject laterally the spray thrown back from theshelf l5.

As will be clear from Fig. 5, the flap i3 is connected at its rear endto a fixed portion ll of running up the sides and over the top of thehull and deflect spray during planing, so giving extra dynamic waterlift. The aft chine strips 2| are near the bottom of the droppedafterbody H, and assist the afterb-ody to act, as above described, inthe same fashion as that of a conventional flying boat when the flap isprojected. The dropped chine strips 2| also reduce water drag bypreventing water from clinging to the side of the portion of theafterbody above them.

The hull is fitted with a bow plate 23 which can be retracted, forflight, into a recess 24 (Fig. '7) in thehull, so that, as shown in Fig.1, its undersurface is flush with the undersurface of the hull, orprojected, for take-off or landing, to the position shown in Figs. 2 and'7. It is then at a coarse angle of incidence so that it will give highwater lift at low speeds. The purpose of the plate 23 is to lift thenose of the 1 aircraft clear of the water at low speeds, and prevent itdigging in at high speeds, thus preventing bow diving or the throwing ofwater over the pilots coupe. At high planing speeds the plate 23 isnormally well clear of the water.

The plate 23 is supported, at each side, as shown in Figs. '7 and 8, bya pair of links 25, 26, mounted respectively on transverse shafts}? and28 and joined by a pair of top links 29. A screw jack 36 is coupled to apair of cranks SI fixed to of the above-described type set in linelongi-,

tudinally and spaced symmetrically, or substantially so, in relation tothe centre of gravity, the flaps being movable independently fromretracted to projected position, and vice versa, by separate controls.Each of the flaps I I3 is precisely. similar to the flap [3 shown inFigs. 1-8 and is operated in similar fashion to move it from retractedto projected position.

What I claim as my invention and desire to secure by Letters Patent is:

l. A marine aircraft, having a stepless hull of substantially streamlineform conforming generally in shape to the fuselage of an aircraftadapted to alight on land, and comprising a flap accommodated in acavity in the base of said hull near the centre of gravity of theaircraft, said flap being pivoted to the hull for movement about atransverse axis spaced rearwardly from the leading edge of the flap,means for moving said flap about said transverse axis from a retractedposition, in which its undersurface is flush with the undersurface ofthe hull, to a projected position in which the forward end of the flapis accommodated in the cavity and the rear end of the flap projectsbeneath the hull, a wall at the 4 front end of the cavity which servesto reflect backwardly spray thrown forward by the flap, when projected,and ducts in the hull for ejectin laterally from the cavity sprayreflected by said wall.

2. A marine aircraft, having a stepless hull of substantially streamlineform conforming generally in shape to the fuselage of an aircraftadapted to alight on 1and, the undersurface of the stern portion of saidhull being substantially level with the undersurface of the centreportion thereof, and comprising a flap accommodated in a cavity in thebase of said hull near the centre of gravity of the aircraft, said flapbeing pivoted to the hull for movement about a transverse axis spacedrearwardly from the leading edge of the-flap, means for moving said flapabout said transverse axis from a retracted position, in which itsundersurface is flush with the undersurface of the hull, to a projectedposition in which the forward end of the flap is accommodated in thecavity and the rear end of the flap projects beneath the hull, a wall atthe front end of the cavity which serves to reflect backwardly spraythrown forward by the flap, when projected, and ducts in the hull forejecting laterally from the cavity spray reflected by saidwall.

3. A marine aircraft, having a stepless hull of substantially streamlineform conforming generally in shape to the, fuselage of an aircraftadapted to alight on land, and comprising a flap accommodated in acavity in the base of said hull near the centre of gravity of theaircraft, said flap being pivoted to the hull for movement about atransverse axis spaced rearwardly from the leadingv edge of the flap,means for moving said flap about said transverse axis from a retractedposition, in which its undersurface is flush with the undersurface ofthe hull, to a projected position in which the forward end of the flapis accommodated in the cavity and the rear end of the flap projectsbeneath the hull, a wall at the front end of the cavity which serves toreflect backwardly spray thrown forward by the flap, when projected,ducts in the hull for ejecting laterally from the cavity spray reflectedby said wall, a plate located beneath the extreme bow portion only ofsaid hull, said platebeing normally housed in a recess in said hull, andmeans for projecting said plate to a position beneath the hull in whichsaid plate is at a coarse angle of incidence to the water.

4. Amarine aircraft, having a stepless hull of substantially streamlineform conforming generally in shape to the fuselage of an aircraftadapted to alight on land, and comprising a plurality of flaps arrangedin line in the'fore and aft direction and disposed substantiallysymmetrically with regard to the centre of gravity of the aircraft, eachof said flaps being accominodated in a cavity in the base of said hullnear the centre of gravity of the aircraft, said flaps being pivoted tothe hull for movement about a transverse axis spaced rearwardly from theleading edge of the flap, means for moving each of said flaps about itspivotal axis from a retra t position in which its undersurface is flushwith he u de surface of the hull, to a projected position in which theforward end of the flap i commodated in the cavity and the rear end ofthe p p ojects beneath the hull, walls at the front ends of saidcavities for reflecting backwardly Dray thrown forward by the flaps,when pro- Jected, and ducts in the hull for ejecting laterally UNITEDSTATES PATENTS Name Sloper Nov. 30, 1915 Number D t 10 Nuggge;

Name Date Smith Jan. 4, 1916 Steinmetz Oct. 3, 1916 Van Wienen Apr. 3,1928 Winter Sept. 6, 1932 Parker May 2, 1944 Bortner Aug. 311, 1948FOREIGN PATENTS Country Date France May 20, 1922

